﻿namespace SystemScanningGui
{
	using System;
	using System.Windows.Data;

	/// <summary>
	/// Two way IValueConverter that lets you bind a property on a bindable object
	/// that can be an empty string value to a dependency property that should 
	/// be set to null in that case
	/// </summary>
	public class TargetNullValueConverter : IValueConverter
	{
		/// <summary>
		/// Converts <c>null</c> or empty strings to <c>null</c>.
		/// </summary>
		/// <param name="value">The value to convert.</param>
		/// <param name="targetType">The expected type of the result (ignored).</param>
		/// <param name="parameter">Optional parameter (ignored).</param>
		/// <param name="culture">The culture for the conversion (ignored).</param>
		/// <returns>If the <paramref name="value"/>is <c>null</c> or empty, this method returns <c>null</c> otherwise it returns the <paramref name="value"/>.</returns>
		public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
		{
			string strValue = value as string;

			return string.IsNullOrEmpty(strValue) ? null : value;
		}

		/// <summary>
		/// Converts <c>null</c> back to <see cref="String.Empty"/>.
		/// </summary>
		/// <param name="value">The value to convert.</param>
		/// <param name="targetType">The expected type of the result (ignored).</param>
		/// <param name="parameter">Optional parameter (ignored).</param>
		/// <param name="culture">The culture for the conversion (ignored).</param>
		/// <returns>If <paramref name="value"/> is <c>null</c>, it returns <see cref="String.Empty"/> otherwise <paramref name="value"/>.</returns>
		public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
		{
			return value ?? string.Empty;
		}
	}
}
